Related Party Transactions (Details) $ in Millions | 3 Months Ended | |
Dec. 31, 2020USD ($)Lot | Dec. 31, 2019USD ($)Lot | Sep. 30, 2020USD ($)Lot |
Related Party Transaction [Line Items] | | | |
Number of Units in Real Estate Property | Lot | 77,500 | | 60,500 |
Number of Lots Sold | Lot | 3,567 | 2,422 | |
Real estate | $ 1,540.5 | | $ 1,309.7 |
D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party | 1.1 | $ 1.3 | |
Related Party Transaction, Expenses from Transactions with Related Party | 1 | 0.6 | |
Due to Related Parties, Current | 1.4 | | $ 8.4 |
Deferred Revenue, Period Increase (Decrease) | 0.2 | (1.5) | |
Related Party Transaction, Purchases from Related Party | 1.7 | 1.5 | |
Costs and Expenses, Related Party | $ 1.1 | $ 1 | |
D.R. Horton, Inc. [Member] | Maximum [Member] | | | |
Related Party Transaction [Line Items] | | | |
Related Party Transaction, Rate | 16.00% | | |
D.R. Horton, Inc. [Member] | Minimum [Member] | | | |
Related Party Transaction [Line Items] | | | |
Related Party Transaction, Rate | 12.00% | | |
D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Number of Lots Sold | Lot | 3,389 | 2,390 | |
Revenue from Related Parties | $ 294 | $ 215.6 | |
Under Contract [Member] | D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Number of Units in Real Estate Property | Lot | 18,300 | | 14,000 |
Related Party Transaction, Purchase Obligation from Parent | $ 1,319.3 | | $ 1,022.2 |
Under Contract [Member] | D.R. Horton, Inc. [Member] | Notes Payable, Other Payables | | | |
Related Party Transaction [Line Items] | | | |
Related Party Deposit Liabilities | 3.8 | | 4.8 |
Under Contract [Member] | D.R. Horton, Inc. [Member] | Cash | | | |
Related Party Transaction [Line Items] | | | |
Related Party Deposit Liabilities | $ 111.7 | | $ 92.2 |
Right of First Offer [Member] | D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Number of Units in Real Estate Property | Lot | 16,600 | | 16,400 |
Land [Member] | | | |
Related Party Transaction [Line Items] | | | |
Real estate | $ 55.5 | | $ 5.4 |
Other Expense [Member] | D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Related Party Transaction, Amounts of Transaction | 20.9 | 5.2 | |
Deposits [Member] | D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Related Party Transaction, Amounts of Transaction | $ 16.1 | $ 10.7 | |
Land [Member] | D.R. Horton, Inc. [Member] | | | |
Related Party Transaction [Line Items] | | | |
Number of Lots Sold | Lot | 0 | 36 | |
Revenue from Related Parties | $ 0 | $ 7.2 | |
Real Estate [Member] | Residential Real Estate [Member] | | | |
Related Party Transaction [Line Items] | | | |
Revenue from Contract with Customer, Including Assessed Tax | $ 307 | $ 217.1 | |